This invention relates to a support structure for supporting a document holder on a main body of a copier, a facsimile apparatus, or like image forming apparatus and, more particularly to a support structure for a document holder suitable in the case where the document holder carries an automatic document feeder.
FIG. 4 shows a fragmentary sectional view of an image forming apparatus such as a copier and a facsimile apparatus. On the top of this image forming apparatus is provided openably and closably a document holder 6 for holding a document (not shown) placed on a document platen 91.
A housing 8 for a main body 9 of the image forming apparatus is made of resin. At a rear end portion (a right end portion in FIG. 4) of an upper surface 8a of the housing 8, there is a support frame 31 in the shape of a relatively long box formed integrally with the upper surface 8a. The frame 31 is open upward. A metal support column 7 connected to an opening/closing mechanism 61 for the document holder 6 is fitted into the support frame 31, and thereby the document holder 6 is attached to the main body 9.
The document holder 6 carries an automatic document feeder (hereinafter referred to as an ADF) constructed so as to feed a document to a specified position on the document platen 91 by means of a transport belt 64. The document holder 6 of this type is charged with static charges generated by the friction between the document and the transport belt 64 or the like, and has conventionally required to be grounded to a frame of the main body 9 through the support column 7 lest an operator should receive an electric shock.
However, the conventional support frame 31 is integrally formed with the upper surface 8a made of resin as described above. The frame of the main body 9 is adapted for fixedly holding respective members used for image formation in specified positions. Accordingly, the support frame 31 and the frame of the main body 9 are basically fixedly positioned relative to each other. Normally, the support frame 31 is spaced apart from the frame of the main body 9 by a specified distance in consideration of the operability of the image forming apparatus.
In view of the above, in the conventional image forming apparatus, an electrode is provided in the support frame 31 formed of resin, and a lead wire is provided between this electrode and the frame of the main body 9. By bringing the support column 7 into direct contact with the electrode, the document holder 6 is grounded through the lead wire. The conventional way of grounding is cumbersome and time-consuming, thereby resulting in an increased manufacturing cost.
This problem may be solved by forming the housing 8 entirely of metal and grounding the document holder 6 through the housing 8. However, this increases the weight of the image forming apparatus. Further, this is unnecessary and causes an increase in the manufacturing cost for the document holder 6 not carrying the ADF.